In an existing LTE (Long Term Evolution) system, an OFDMA (orthogonal frequency division multiple access) technology is usually used for downlink. To effectively promote cell-center and cell-edge throughputs, a NOMA (non-orthogonal multiple access) technology is a potential candidate technology. When the NOMA is used for communication, a base station allocates different powers to different user equipments (UE). However, different UEs may use a same frequency resource.
Two or multiple UEs using a same time frequency resource block to communicate with a base station are referred to as paired UEs. For example, when using the NOMA technology, a UE1 and a UE2 use a same time frequency resource block to communicate with a base station, and the UE2 and the UE1 are paired UEs. The base station uses different transmit powers to send signals to the UE1 and the UE2. There is interference between a downlink signal for the UE1 and a downlink signal for the UE2. The downlink generally refers to a direction from a base station to a UE. To effectively extract the downlink signal for the UE1, the UE1 needs to eliminate interference from the downlink signal for the UE2. In the prior art, the UE1 cannot obtain related information of the downlink signal for the UE2, and cannot use the NOMA technology to communicate.